Kilocalories to Calories Converter
Common Conversions
| kcal | cal |
|---|---|
| 0.001 | 1 |
| 0.01 | 10 |
| 0.1 | 100 |
| 0.5 | 500 |
| 1 | 1000 |
| 2 | 2000 |
| 5 | 5000 |
| 10 | 10000 |
| 50 | 50000 |
| 100 | 100000 |
| 500 | 500000 |
| 1000 | 1000000 |
Why this conversion matters in chemistry
Consider indirect calorimetry data. A clinical metabolic-cart measurement of 1800 kcal/day resting metabolic rate is 1.8 × 10⁶ cal/day on the underlying VO₂ math — the Weir equation runs in cal before aggregating up to the kcal/day clinical-report number. That 1000 cal per kcal is the kilo prefix, no more. The conversion sits at the handoff between dietary-style kcal data and the small-calorie units a textbook q = mcΔT problem expects.
Formula
cal = kcal × 1000
Worked Examples
1 kcal = 1000 cal
The conversion anchor — equivalently 1 food Calorie.
80 kcal = 80000 cal
Heat of fusion of 1 kg of ice — about 80 cal/g for the phase change.
540 kcal = 540000 cal
Heat of vaporization of 1 kg of water at 100 °C.
68.31 kcal = 68310 cal
Combustion of 1 mol of hydrogen gas to liquid water — a classic textbook reference.
Frequently Asked Questions
How do I convert kcal to cal?
Multiply by 1000. So 5 kcal becomes 5000 cal. The relationship is exact through the kilo prefix. 1 kcal also equals 4184 J or 1 food Calorie.
Why does the food Calorie capitalize the C?
Nutrition labels use 'Calorie' (capital C) as a shorthand for one kilocalorie of metabolizable energy. The convention predates modern SI usage and traces to Atwater's 19th-century food-energy work. Chemistry uses the lowercase 'calorie' (= 4.184 J) for laboratory thermochemistry.
What's the difference between cal, Cal, and kcal?
A small calorie (cal) is 4.184 J. A food Calorie (Cal, capitalized) is 1 kilocalorie (kcal) = 1000 cal = 4184 J. The capital-C convention on food labels always means kcal — getting it wrong gives a 1000× error.